Here’s a general rule. When an insult is directed at a woman, consider how it would have sounded directed at a man. If the result is ridiculous, then it’s probably sexist.
Some teachers still have trouble showing any sort of vulnerability of fallibility. These teachers will expend immense amounts of energy hiding the fact they’re frustrated at something, that they’re upset or perhaps even angry. Why? Other teachers get tied into logical knots to avoid admitting “I have no idea what the answer to your question is.” But teachers who genuinely connect with students are the ones who aren’t afraid to show emotions in class, who can admit that they aren’t in fact the repository of all knowledge. Of course nobody want to be a wallowing, blubbering mess in class, but what better way to teach empathy than to give the students someone to empathize with when we’re having a bad day? What better way to foster collaboration and to teach that it’s okay not to know something than to say “I don’t know, let’s find that out!”?